Ferns dropping leaves can be caused by various factors. Identifying the cause is crucial to solve the issue and prevent it from happening again. Here are some common reasons for ferns dropping leaves and how to address them:

1. Underwatering: If the soil dries out too much, ferns may drop leaves as a response to stress. Ensure that you keep the soil evenly moist but not soggy. Check the soil frequently, and water when the top 1-2 inches feel dry to the touch.

2. Overwatering: Overwatering can cause root rot and lead to the plant shedding leaves. Make sure you're not overwatering your fern and that the soil drains well. Allow the top 1-2 inches of soil to dry slightly between waterings. If root rot is suspected, trim away any affected roots and repot the fern in fresh, well-draining soil.

3. Low humidity: Ferns prefer high humidity levels, and if the air is too dry, they may drop leaves. Increase the humidity around your fern by placing a tray of water near the plant, misting the leaves regularly, or using a humidifier.

4. Temperature stress: Extreme temperature fluctuations or exposure to cold drafts can cause ferns to drop leaves. Maintain a stable temperature, ideally between 60-75°F (15-24°C), and keep your fern away from cold drafts or heating vents.

5. Insufficient light: Ferns generally prefer bright, indirect light. If they don't receive enough light, they may shed leaves. Move your fern to a location with appropriate light levels. Remember that different fern species have varying light requirements, so it's essential to research the specific needs of your fern.

6. Nutrient deficiency: A lack of essential nutrients can cause ferns to drop leaves. Apply a balanced, water-soluble fertilizer at half strength every 4-6 weeks during the growing season to provide necessary nutrients.

7. Pests: Pests like spider mites, aphids, and mealybugs can cause ferns to shed leaves. Inspect your fern regularly for signs of pests and treat any infestations promptly using insecticidal soap, neem oil, or other appropriate methods.

8. Aging: It's natural for older fern fronds to die off and be replaced by new growth. If the dropping leaves are limited to older fronds and the plant appears otherwise healthy, this may be a normal part of the fern's life cycle.

To solve the issue of dropping leaves, identify the underlying cause and address it accordingly. Maintain proper care, including appropriate watering, humidity, lighting, and pest control, to keep your fern healthy and prevent future leaf drop.